1.1 Background to the Study
Groundnut (Arachis hypogaea) is a species in the legume or beans family (Ashish and Handa, 2014; Atiku et al., 2014). It was first cultivated in Peru. Its seed contain about 63% carbohydrate, 19% protein and 6.5% oil. Groundnuts are grown in tropical and subtropical climate regions and warmer parts of temperature regions and it is low growing annual plant and has a variety of uses. Prior to its usage however groundnut need to undergo preprocessing which include drying and shelling. Removing of kernels from the pod is generally referred to as shelling or “decorticating” (Maduako et al., 2006). In Nigeria groundnut is mainly decorticate by hands (traditional method). This method is not hygienic as dirt from hands and mouth could pose health risk from the nuts. (FAO. 2001). Shelling is a fundamental step in groundnut processing as it allows the kernel and hull to be used as well as other post harvesting technologies to take place such as oil extraction or in hull briquetting (Pradhanaet al., 2010). Shelling is usually carried out on the farm just before the farmer sells his product for the following reasons: Kernel do not store as well as nuts in the shell and groundnuts in the shell are fifty per cent heavier than kernels alone and therefore costlier to transport. Shelling can generally be done by hand or machine. Hand shelling is the process in which the pod is pressed between the thumb and first finger so that the kernel is released. In mechanization now we use large and smaller machinery for groundnut shelling. These machines are used in industries where large production is required. There are different methods of shelling and different machines have been fabricated and used to shell wide variety of crops under different conditions (Nyeaanga et al., 2003., Atiku et al., 2004; Gitau et al., 2013; and Maduakoet al., 2006). The peasant farmer cannot afford this machine because they are too costly and complex in operation and maintenance. Also the operator had to be trained and spare part imported. These factor increase the overall cost production which does not make any economic sense to the farmer.
1.2 Statement of the Problems
Research shows that groundnut has an inherent poor storage life, if not threshed after harvesting unlike some other crops, but in threshed forms, it can be stored for a very long period of time (Onuoha 2010). Therefore, to overcome the problem associated with manual threshing and quick rate of insect infestation after harvesting, the development of groundnut decorticating machine is of paramount. Traditionally the seeds are left in the pods which would then be stored in a pot and would only be shelled when they are needed for cooking (Ngugi, 2007), shelling is one by hand or beating with a short stick or pestle and mortar, followed by winnowing (Kaul and Egbo,1985). The constraints such as fatigue, high time energy inputs and inefficiency in manual shelling of groundnut led to design and fabrication of pedal operated groundnut Sheller that will go a long way in solving the problem of rural farmers that are engage in groundnut production at small and medium scale level.